<!DOCTYPE html>
<html lang="en">

  <head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>HTML5新增</title>
  </head>

  <body>
    <ol class="ois">
      <li>1</li>
      <li>2</li>
      <li>3</li>
      <li>4</li>
      <li>5</li>
    </ol>
  </body>
  <script>
    /* 
    HTML5新增的三种方式：
     1.document.getElementsByClassName()
     2.document.querySelecoter();
     3.document.querySelectorAll();
    */
    var ols2 = document.getElementsByClassName("ois");
    var ols1 = document.querySelector(".ois");
    var lis = document.querySelectorAll("li");
    console.log(ols2);
    console.log(ols1);
    console.log(lis);
  </script>

</html>